To say that September is a bad month for stocks is putting it lightly. Actually, “it is widely viewed as a rotten month for stocks,” according to Wall Street veteran Ed Yardeni, and for good reason. Since 1945, the S&P 500 has dropped 0.73% on average in September. That’s compared with an average monthly gain of 0.7% for the index across all months over the same period.

The Guardian’s economics editor Larry Elliott went a step further earlier this month, reminding readers that the coming of autumn has coincided with such financial disasters as the bankruptcy of Lehman Brothers in 2008, the Great Depression–era demise of the gold standard, even the mother of all financial crashes: the collapse of the South Sea Bubble in 1720.

Still, if you ask the president and chief investment strategist of Yardeni Research how to invest in the market during September, he won’t recommend running for the hills. September may be a rotten month for market returns historically, but Yardeni maintains that it’s also a good time to find long-term bargains.

“September is a good month for picking apples,” Yardeni explained in a September 5 note to clients. “Selloffs have often turned out to be good opportunities to pick fallen stocks just in time for a year-end Santa Claus rally.”

Yardeni has argued throughout 2023 that despite consistent recession forecasts from investment banks and economists, the economy is unlikely to face a serious downturn as a result of the Federal Reserve’s interest rate hikes. Interest-rate-sensitive sectors of the economy like housing are already contracting, according to Yardeni, but other sectors that aren’t as affected by rates are continuing to grow, helping to prevent an economy-wide recession. Additionally, baby boomers’ unprecedented $75 trillion net worth is helping consumer spending remain robust even as the labor market cools under the weight of higher interest rates.

Despite stocks’ tendency to underperform in September, Yardeni clearly isn’t bearish about the future of the market. Still, the veteran market watcher decided to break down seven ways things could go wrong for stocks this month in order to keep investors informed of the risks. Here’s what he had to say.

1. Rising bond yields

First, Yardeni is worried that rising bond yields could reduce stocks’ appeal for investors, leading to a drop in share prices. When the yield on the 10-year U.S. Treasury approaches 5%, many investors become enamored by the stable, nearly risk-free returns on offer and forgo investing in equities. And with oil prices rising, the Fed may be forced to hike interest rates again, which would send the 10-year, currently 4.29%, toward 5%.

2. High oil prices

Oil prices have risen 30% from their March lows around $67 per barrel to over $87 on September 6. Rising oil prices could keep inflation elevated, forcing the Federal Reserve to continue raising interest rates to ensure price stability for consumers. And after more than 17 months of interest rate hikes that have raised the cost of borrowing nationwide, many experts fear the economy can only take so much more.

Yardeni also noted that earlier this week Saudi Arabia extended its voluntary crude production cuts of 1 million barrels per day through year-end, which could cut oil supply. And China’s government put forward several measures to stimulate its ailing economy, including relaxing home purchase restrictions and lowering interest rates, which could boost oil demand. “These developments heighten inflationary concerns,” he warned.

3. A higher-than-expected inflation reading

August’s consumer price index (CPI) data comes out on September 13, and if it doesn’t show fading inflationary pressures, it could be a problem for stocks. Investors hoping that the Fed is nearing the end of its economy-slowing interest rate hiking campaign could be in for a surprise.

“The jitters over the CPI on September 13 are likely to increase in the coming days,” Yardeni wrote, explaining that depending on which data source you look at, there could be a higher- or lower-than-expected inflation print.

“Truflation is tracking a 2.5% y/y [year-over-year] increase, which would be a very happy surprise indeed,” he said. “The Cleveland Fed’s CPI tracker has the headline and core rates at 3.8% and 4.5%, which would be unhappy surprises.”

4. The Federal Open Market Committee meeting

The FOMC is set to meet on Sept. 19 and 20 to decide interest rate policy in the U.S. If its members decide to raise interest rates again, that will undoubtedly be bad for stocks. But even if they don’t, just a hawkish tone from Fed Chair Jerome Powell could send equities lower as investors will begin to forecast “higher for longer” interest rates that typically weigh on economic growth.

“Even the FOMC’s participants don’t know what they will decide at their next meeting,” Yardeni explained, arguing that the indecisiveness has created jitters among investors.

5. A United Auto Workers strike

Ford, GM, and Stellantis are facing a workers strike after the UAW demanded a new contract with pay increases, a 32-hour workweek, and other costly initiatives, but was rebuked by the companies. As Fortune previously reported, the UAW strike has left Detroit’s Big Three in a pickle. They can either allow the strike to move forward or accept billions in incremental cost increases that would force them to hike car prices, which could hinder demand.

Yardeni backed up that reporting, saying: “The UAW is likely to go on strike against all three of Detroit’s automakers at the end of the month. That could depress the economy depending on how long it lasts and drive up car prices.”

6. A federal government shutdown

Political gridlock in Washington has led to many unproductive budget deficit talks over the past few years. Just last year, lawmakers narrowly avoided a government shutdown after disagreements over the size and scope of federal spending. Ultimately, they agreed on a $1.7 trillion spending bill that will keep the government running through the end of this month, but that means another showdown is on the way.

“Republican hardliners are playing a game of chicken with Republican moderates and Democrats over the federal budget. Instead of a compromise, the result could be a government shutdown, possibly by the end of the month, but more likely in October,” Yardeni wrote.

7. China’s ailing economy

Finally, “Government efforts are underway to stimulate the economy. If those efforts fail, oil prices could fall again and China would be a major source of global deflation,” Yardeni wrote. While many economies around the world are currently battling inflation, deflation is an equally deadly, or some would argue even more deadly, economic disease. After all, deflating economies are typically contracting economies, and that means rising unemployment.